Embossed, cross-laminated film

ABSTRACT

A moisture resistant film is for covering an architectural structure. The film includes a flexible membrane defining a plane and a first plurality of spaced apart, discrete embossings formed in the membrane extending outwardly of the plane. The embossings are formed in rows in an x-direction and in columns in a y-direction. The rows are parallel to and spaced from one another and the columns are parallel to and spaced from one another. A method and tool for making the film are also disclosed.

BACKGROUND OF THE INVENTION

The present invention relates to an embossed cross-laminated film orsheet construction. More particularly, the present invention relates toa sheet formed from a laminate of two cross-oriented films that isembossed to form a three-dimensional engineered surface material for useas a construction moisture barrier.

In the construction of buildings such as houses and the like, moistureand air barriers are used between the house framing and the outercovering, e.g., siding or clapboard. These barriers are used to preventthe intrusion of moisture into the areas of the building between theframing or inner walls and the outer house covering.

Moisture ingress between the outer covering and the framing or walls ofa house can be problematic. For example, molds and fungus have beenlinked to the presence of water in certain areas of buildings. As such,there have been considerable efforts made to create barriers that notonly prevent the ingress or intrusion of water (as bulk water andmoisture or condensate) but also direct such water away from theinterior walls to enhance drainage, prevent pooling and to reduce theopportunity for mold and fungus growth.

Barrier materials, also referred to as “house-wraps”, are installedbetween frame sheathing surfaces and exterior covering or claddingproducts to provide a secondary layer of protection from moistureintrusion. This weather resistive barrier function can be furtherenhanced to promote drainage of moisture and the flow of air, to reducethe likelihood that water will penetrate further into the wall assemblywhere wetting of the substrate and framing materials could likely occur.Elevated moisture levels in these areas could contribute to mold growthand/or wood decay and ultimately increase the potential for structuralfailure.

Recently, house-wrap barrier materials have been developed that includedrip channels or drainage channels to promote moisture drainage.However, these channels are direction dependent. That is, because of thegeometry of the material and the geometry and “shape” of the channelsformed in the material, in order for the material to function properly(that is, to drain properly), the material must be installed in acertain orientation or direction on the structure or building. In theevent that the material is improperly installed, liquid can continue topool and moisture or liquid intrusion can occur.

Moreover, known house-wrap materials are formed from woven materials.These materials tend to impart high tear resistance, which is highlydesirable in the construction industry. However, such materials can beexpensive to manufacture and are typically more permeable (to liquidwater as opposed to water vapor) than non-woven materials.

Accordingly, there is a need for a house-wrap material having a highlevel of moisture resistance. Desirably, such a material has structurethat permits it to direct water away from the interior regions of thestructure to which it is installed. More desirably, such a materialfunctions independent of the orientation at which it is installed on thestructure. Most desirably, such a material has a high tear resistanceand high overall strength to permit use in a wide variety ofconstruction situations and at a wide variety of sites.

SUMMARY OF THE INVENTION

A moisture resistant house-wrap film is configured for covering anarchitectural structure. The house-wrap is formed from a flexiblemembrane defining a plane having a first plurality of spaced apart,discrete embossings formed in the membrane extending outwardly of theplane. The embossings are formed in rows in a (general) x-direction andin columns in a (general) y-direction. Preferably, a plurality of rowsand a plurality of columns are formed. The rows are spaced from oneanother and the columns are spaced from one another. In a most preferredhouse-wrap, the rows and columns are non-rectilinear.

Such a house-wrap material has a high level of moisture resistance incombination with structure that permits it to direct water away from theinterior regions of the structure to which it is installed. Such amaterial functions independent of the orientation at which it isinstalled on the structure and has a high tear resistance and highoverall strength to permit use in a wide variety of constructionsituations and at a wide variety of sites.

In a preferred house-wrap, the rows are formed in parallel curvedpatterns and the columns are formed in parallel curved patterns. Mostpreferably, the curves (in both the x- and y-directions) are sine wavepatterns. A present house-wrap has the first plurality of spaced apartdiscrete embossings formed transverse to the plane in a first directionand a second plurality of spaced apart, discrete embossings formed inthe membrane extending outwardly of the plane in a second directionopposite of the first direction. The embossings are formed in rows inthe x-direction and in columns in the y-direction. The rows and columnsare non-rectlinear. In such a pattern, the rows and columns of the firstplurality of embossings are spaced from one another by rows and columnsof the second plurality of embossings. Non-embossed neutral spaces aredisposed between each of the first plurality of spaced apart discreteembossings and between each of the second plurality of spaced apartdiscrete embossings. A present embossing has a truncated, pyramidalparallelogram shape.

A preferred film has the flexible membrane formed as a multi-layerlamination having a first oriented plastic layer and a second orientedplastic layer. The oriented plastic layers cross at an angle between butnot equal to zero degrees and 180 degrees relative to one another.Preferably the layers are at an angle between 40 degrees and 140 degreesrelative to the orientation of the other plastic layer, and mostpreferably, the layers are at an angle of orientation of about 90degrees to one another.

Such a membrane has first and second plastic layers that arepolyolefins, and preferably polyethylene. A bonding media can bedisposed between the plastic layers.

A method of forming the moisture resistant flexible film includes thesteps of laminating a first oriented plastic layer and a second orientedplastic layer to one another where the orientations of the first andsecond layers cross at an angle between but not equal to zero degreesand 180 degrees to form a flexible membrane defining a plane. The methodincludes forming in the flexible membrane a first plurality of spacedapart, discrete embossings extending outwardly of the plane. Theembossings are formed in rows in an x-direction and in columns in ay-direction. In a preferred method, the rows and columns arenon-rectilinear.

In a preferred method, in the forming step, the first plurality ofspaced apart discrete embossings are formed transverse to the plane in afirst direction and a second plurality of spaced apart, discreteembossings are formed in the membrane extending outwardly of the planein a second direction opposite of the first direction. In such a method,the embossings are formed in rows in an x-direction and in columns in ay-direction. Preferably, the rows and columns are non-rectilinear, andthe rows and columns of the first plurality of embossings are spacedfrom one another by rows and columns of the second plurality ofembossings.

A tool for forming the embossings includes a roller having a pluralityof embossing projections extending therefrom defining alternating firstrows of alternating first direction embossing projections and neutralspaces and intermediate alternating second rows of second directionembossing projections (which second direction embossings are actuallycavities) and neutral spaces. The alternating first rows of firstdirection embossing projections and neutral spaces are disposed to formalternating first columns of first direction embossing projections andneutral spaces and the intermediate alternating second rows of seconddirection embossing cavities and neutral spaces are disposed to formalternating second columns of second direction embossing cavities andneutral spaces. In a present tool, the first rows of first directionembossing projections and neutral spaces and second rows of seconddirection embossing cavities and neutral spaces are non-rectilinear andare parallel to one another and the first columns of first directionembossing projections and neutral spaces and second columns of seconddirection embossing cavities and neutral spaces are non-rectilinear andare parallel to one another. A present tool has a second mating rollerhaving a mating profile.

These and other features and advantages of the present invention will bereadily apparent from the following detailed description, in conjunctionwith the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The benefits and advantages of the present invention will become morereadily apparent to those of ordinary skill in the relevant art afterreviewing the following detailed description and accompanying drawings,wherein:

FIG. 1 is a perspective illustration of a tool (a pair of rollers),embodying one aspect of the present invention, for forming an embossedcross-laminated house-wrap film also of the present invention;

FIG. 2 illustrates, schematically, the formation of the tool embossingelement locations;

FIG. 3 illustrates the position, pattern and formation of the embossingelements of the tool;

FIG. 4 illustrates one embodiment of the film as formed having a doublesine wave embossing pattern formed therein;

FIG. 5 is an enlarged illustration of the film of FIG. 4;

FIG. 6 is an enlarged view of the film of FIG. 5;

FIG. 7 illustrates sections of the embossing tool used to produce thefilm shown in FIGS. 5 and 6;

FIG. 8 illustrates a portion of the film sheet;

FIG. 9 is a cross-section of the sheet taken along line 9-9 of FIG. 8;

FIG. 10 is a cross-section of the sheet taken along line 10-10 of FIG.8;

FIG. 11 is a schematic illustration of a building having the embossedcross-laminated house-wrap film installed thereon;

FIG. 12 is a schematic illustration of a process for forming thehouse-wrap film;

FIG. 13 is an enlarged view of a portion of an alternate tool forforming an alternate embossing in the film;

FIG. 14 is a cross-section of the alternate film;

FIG. 15 is a view of the top or bottom surface of the alternate film;and

FIG. 16 is an exploded perspective view of a the multi-layer laminationused in the film of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

While the present invention is susceptible of embodiment in variousforms, there is shown in the drawings and will hereinafter be describeda presently preferred embodiment with the understanding that the presentdisclosure is to be considered an exemplification of the invention andis not intended to limit the invention to the specific embodimentillustrated.

It should be understood that the title of this section of thisspecification, namely, “Detailed Description Of The Invention”, relatesto a requirement of the United States Patent Office, and does not imply,nor should be inferred to limit the subject matter disclosed herein.

Referring now to the figures and briefly, to FIG. 8, there is shown oneembodiment of an embossed, cross-laminated film 10, or house-wrapembodying the principles of the present invention. The house-wrap film10 is shown positioned on a building B in FIG. 11. The house-wrapmaterial 10 has a high level of moisture resistance and, as is describedbelow, has a structure or engineered surface that permits it to channelwater away from the interface of the material and the structure to whichit is installed.

The house-wrap material 10 has an engineered surface that provides botha stand-off effect which precludes pooling or ponding, for example,along a ridge formed where house siding rests on the underlying housestructure, and orientation independent channels 12 (see FIG. 8) topermit moisture (e.g., water) to dram from the surface of the wrap 10.

The wrap material 10 is preferably a cross-laminate of uniaxiallyoriented films from crystalline polymers. Such materials are known toexhibit a number of beneficial properties including improved tearresistance. One example of a multi-layer, oriented or “bias-cut” plasticfilm is disclosed in Barnes et al., U.S. Pat. No. 6,284,344, which iscommonly assigned with the present invention and which is incorporatedherein by reference.

A preferred material is VALERON® brand film commercially available fromITW VALERON® of Houston, Tex. Referring to FIG. 16, the film 14 (alsoreferred to as a web) is a polyolefin, preferably a high densitypolyethylene (HDPE) material that is formed from a cross-laminate of twofilm layers 16, 18 that are each extruded and bias cut in a continuousspiral to obtain molecular orientation at an angle to a roller ontowhich the film is collected The bias cut films 16, 18 are thencross-laminated, preferably with an adhesive or polymer 20 between thefilm layers 16, 18 to form the web 14. Other non-woven materials, suchas polyethylene terephthalate (PET), and coextruded polymeric materialsare contemplated for use in the embossed house-wrap film.

As seen in FIG. 16, the direction of orientation of the first film layer16 crosses the direction of orientation of the second film layer 18 at apredetermined angle α such that the orientations of the layers 16, 18are non-parallel. That is, the film layer orientations cross one anotherat an angle α between but not equal to zero degrees and 180 degrees. Asseen in FIG. 16, the orientation of layer 16 is indicated by the linesat 22 and the orientation of layer 18 is indicated by the lines at 24.The angle α can range from about 40 degrees to about 140 degrees, andpreferably ranges from about 78 degrees to about 104 degrees. A mostpreferred orientation angle is about 90 degrees so that the films 16, 18are oriented perpendicular to one another. A preferred laminate web 14has a thickness of about 3.2 thousandths of an inch (0.0032 inches or3.2 mils) to about 4.0 mils. The web 14 can, of course be formed havingother thicknesses, depending upon the desired application; however, ithas been found that these web gauges or thicknesses function well forconventional residential construction.

Following cross-lamination, the web 14 has an engineered surface formedtherein. A present surface is formed by embossing the web 14 to form thefilm 10. Embossings are formed in each direction of the web 14 relativeto the plane P₁₀ of the film 10. That is, relative to the plane P₁₀ ofthe film 10 (being the plane of the drawing of FIGS. 5 and 8), theembossings are formed out of the plane of the paper (for purposes ofdiscussion, this is referred to as a positive embossing 30) and into theplane of the paper (a negative embossing 34). When viewing the surfaceof the web 10, the embossings define positive embossings 30 and negativeembossings 34 having a neutral region 32 for those areas that are notembossed. The embossings 30, 34 are formed in the z-direction of thefilm 10. It will be appreciated by those skilled in the art that what isviewed as a positive embossing 30 on one “side” of the film 10 is anegative embossing 34 on the other side of the film 10.

The embossings 30, 34 are configured in predetermined patterns in boththe x-direction (or rows, indicated generally at 26) and the y-direction(or columns, indicated generally at 28) of the film 10. In a presentfilm 10, neither the rows 26 nor the columns 28 are straight. Rather, asillustrated, the rows 26 and columns 28 are formed from discreteembossed 30, 34 elements disposed, as discussed below, in sine wavepatterns. Each row 26 and each column 28 is formed from alternatingpositive embossings 30 and neutral plane regions or areas 32 or negativeembossings 34 and neutral plane areas 32, with the rows 26 (or columns28) staggered so that each region (that is, each embossing 30, 34 oreach neutral area 32) is adjacent an unlike region. That is, becausehalf of the regions in each row 26 and in each column 28 are neutralareas 32, the rows 26 (and columns 28) are formed relative to oneanother such that the neutral areas 32 do not share a common edge, butare staggered relative to one another (touching at their respectivecorners).

For example, referring to FIG. 8, the positive embossings of row RA(embossings RA1-RA10) are spaced from adjacent positive embossings inthat row (that is, RA1 is spaced from RA2, which is spaced from RA3, andso on) by the neutral spaces RAS1, RAS2, RAS3, and so on. And, thepositive embossings of row RA are spaced from the positive embossings ofrow RC by the neutral plane areas CAS1, CCS1 and so on. The same patternis followed for the columns. That is, the positive embossings of columnCA (embossings CA1-CA10) are spaced from adjacent positive embossings inthat column (that is, CA1 is spaced from CA2, which is spaced from CA3,and so on) by the neutral spaces CAS1, CAS2, CAS3, and so on. And, thepositive embossings of column CA are spaced from the positive embossingsof column CC by the neutral plane areas CBS1, CBS2 and so on. As shown,the film 10 has at least two rows R (e.g., RA, RB, RC) and at least twocolumns C (e.g., CA, CB, CC). It will be appreciated from the figuresthat the present film 10 is formed having a checkerboard-likeappearance, with about 25 percent of the “spaces” being positiveembossings, about 25 percent of the “spaces” being negative embossings,and about 50 percent of the “spaces” being neutral plane areas orspaces.

It will, also be apparent that because the embossings 30, 34 that formthe rows 26 also are the embossings 30, 34 that form the columns 28,each of the embossings 30, 34 will have a row designation and a columndesignation, and in this manner form a matrix.

As seen in FIG. 5, the rows 26 and the columns 28 are formed in a curvedpattern or having a curved path. That is, the rows 26 and columns 28 donot form a straight line (are not rectilinear). Rather, the rows 26 andcolumns 28 are formed, preferably, having a sinusoidal patter In acontemplated wrap 10, the sine curves have a pitch of about 2.0 inches,and a peak to peak amplitude of about 0.25 inches. The embossings 30, 34are formed having a side length l₃₀ of about 0.05 inches (about 50 mils)and a depth d₃₀ of about 0.035 inches (about 35 mils). The embossing“density” is about 40 embossings 30, 34 per side per repeating pattern(based on a 2 inch pitch) or about 1600 embossings per four squareinches (or about 400 embossings per square inch). In a contemplated film10, the embossings 30, 34 are each formed as a truncated pyramid havinga parallelogram base (see FIG. 10). That is, the embossings 30, 34 areformed having four substantially equal length sides 130 (not necessarilysquare, but in a parallelogram shape, see e.g., FIG. 3), that taperinwardly in the upward direction (away from the neutral plane P₃₂) at anangle α of about 15 degrees.

One tool 36 for forming the embossed film 10 is illustrated in FIGS. 1-2and 7, in which FIG. 7 illustrates two of regions of an embossing roller38. A reference or neutral plane P₃₂ is defined by the roller 38 whichcorresponds to the neutral spaces 32 in the film 10 of FIG. 5.Projections 42 then extend outwardly from the roller 38 a height ordistance d₄₂ of about 35 mils from the neutral plane P₃₂. Theprojections 42 are formed having a truncated square pyramidal shape withthe sides 44 tapering inwardly at an angle β of about 15 degreesrelative to a line perpendicular to the neutral plane P₃₂. The peaks 46of the projections 42 are flat and the valleys 48 between theprojections 42 (at the neutral plane P₃₂) are flat. As will beunderstood, the “projections” 42 form negative embossings 34.

In addition to the projections 42, recesses 50 are also formed in theroller 38 that form the positive embossings 30. The recesses 50 areformed in a mirror image relation to the projections 42; that is, therecesses 50 have a flat base 52 (corresponding to the neutral plane P₃₂)and sides 54 formed at an angle β of about 15 degrees relative to a lineperpendicular to the neutral plane P₃₂.

The film 10 itself exhibits enhanced strength and tear resistance due toits cross-laminated structure. Those skilled in the art will recognizethat the orientation of a plastic layer is a characteristic that isimparted to the film during manufacture. Typically, a polymer is meltedand extruded into a bubble form from an extruder die. The film is thencooled, for example, using an annular air-ring (blown film process). Thecooled bubble is collapsed to form layflat tubing which is thenstretched. It is the extrusion and stretching operations that “orient”the film. Essentially, the long chain polymer molecules are oriented ordirected as a result of the extrusion and stretching processes. Theoriented layflat tubing so produced is then bias cut to produce a singlelayer of film where the orientation angle is at the desired angle to themachine direction.

One process (indicated generally at 60) for making the film 10 isillustrated in part and schematically in FIG. 12. In the film formingportion of the process (which is referred to as an extrusion laminationprocess), a station 62 is used to apply the cross-oriented laminatefilms 16, 18 to one another with a bonding material applicator 64positioned to apply the bonding or adhesive sealing material 20 betweenthe plastic layers 16, 18 at about a roller nip 66. Alternately, theplastic layers 16, 18 can be disposed directly on one another withoutthe use of the bonding or sealing layer. In a contemplated film,however, the bonding layer 20 is disposed between the plastic layers 16,18, which bonding layer 20 is formed from a media, such as low densitypolyethylene or the like.

This process forms a flexible, cross-laminated film or membrane 14,which is then conveyed to a second (or embossing) station 68, at whichthe membrane 14 is fed into the nip 70 of the embossing rollers 38, 40to form the embossed film 10. The film 10 is perforated for permeabilityto permit the passage of water vapor but to preclude the passage ofliquid water.

With respect to the material, it also is contemplated that adhesivelaminations could be used as an alternative to extrusion lamination. Insuch a process, it is anticipated that a polymer (e.g., polyurethane)adhesive system is used. However, other polymeric adhesive systems arealso contemplated. If needed, some arrangement of drying ovens can beused to remove solvents (from the adhesive) or the like.

An alternate embossing pattern 110 is illustrated in FIGS. 13-15. Inthis embodiment 110, the rows 126 and columns 128 are spaced so thatadjacent rows or columns (of pairs of embossings 130, 134) are staggeredrelative to adjacent columns 126, or rows 128.

For example, the embossings in the second row 126B are in columnaralignment with the embossings in the fourth row 126D and the sixth row126F, but are staggered relative to the embossings in the first row126A, the third row 126C, the fifth row 126E, and so on (which are incolumnar alignment with one another). Likewise, the embossings in thefirst column 128A are in row-alignment with the embossings in the thirdcolumn 128C, and so one, but are staggered from those in the secondcolumn 128B, fourth column 128D, and so on.

The embossings 130, 134 are formed as three-dimensional elongated ovalshaving curved or rounded upper and lower ends 136 with elongatedmid-sections 138. Essentially, the embossings 130, 134 have arace-track-like shape. As seen in FIG. 14, when viewed in the directionperpendicular to the plane of the web 110 (i.e., a cross-section), theembossings 130, 134 have curved side walls 140 with flattened peaks 142and troughs 144.

The present house-wrap 10, 110, unlike the continuous channel typeformed in known barrier materials, is formed by discrete, spaced apartformations 30, 34, 130, 134 in the web 14. A present house-wrap film 10,110 functions independent of the orientation at which it is installed onthe structure B. Most desirably, such a material 10, 110 has a high tearresistance and high overall strength to permit use in all constructionsituations and at all sites.

While specific embossing patterns, profiles, shapes and orientationshave been describes, it is to be understood that various other patterns,profiles, shapes and orientations are contemplated by the presentinvention and are within the scope of the present invention.

All patents referred to herein, are hereby incorporated herein byreference, whether or not specifically done so within the text of thisdisclosure.

In the disclosures, the words “a” or “an” are to be taken to includeboth the singular and the plural. Conversely, any reference to pluralitems shall, where appropriate, include the singular.

From the foregoing it will be observed that numerous modification andvariations can be effectuated without departing from the true spirit andscope of the novel concepts of the present invention. It is to beunderstood that no limitation with respect to the specific embodimentsillustrated is intended or should be inferred. The disclosure isintended to cover by the appended claims all such modifications as fallwithin the scope of the claims.

1-20. (canceled)
 21. A method of forming a moisture resistant flexiblefilm comprising the steps of: laminating a first oriented plastic layerand a second oriented plastic layer to one another where theorientations of the first and second layers cross at an angle betweenbut not equal to zero degrees and 180 degrees relative to one another toform a flexible membrane defining a plane; and forming in the flexiblemembrane a first plurality of spaced apart, discrete embossingsextending outwardly of the plane, the embossings formed in rows in anx-direction and in columns in a y-direction, the rows being spaced fromone another and the columns being spaced from one another.
 22. Themethod in accordance with claim 21 wherein the rows and columns arenon-rectilinear.
 23. The method in accordance with claim 21 wherein inthe forming step the first plurality of spaced apart discrete embossingsare formed transverse to the plane in a first direction and a secondplurality of spaced apart, discrete embossings are formed in themembrane extending outwardly of the plane in a second direction oppositeof the first direction, the embossings formed in rows in an x-directionand in columns in a y-direction, the rows and columns of the firstplurality of embossings being spaced from one another by rows andcolumns of the second plurality of embossings.
 24. The method inaccordance with claim 23 wherein the rows and columns arenon-rectilinear. 25-30. (canceled)